Electronic roundsling inspection, load monitoring and warning system

ABSTRACT

An electronic overload inspection and warning system for a roundsling having a strand positioned within a plurality of core strands and a cover. The system includes a wireless sensor system mountable to the roundsling. The wireless sensor system includes at least one strain gauge electrically connected with a wireless transmitter. The strain gauge measures strain on the strand. The system also includes a wireless base station and a carrier element. The wireless base station includes a wireless receiver configured to wirelessly communicate with multiple deployed wireless sensor systems. The carrier element is secured to the strand. The strain gauge is secured to the carrier element.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional PatentApplication No. 62/241,401, filed on Oct. 14, 2015 and titled“Electronic Roundsling Inspection, Load Monitoring and Warning System,”and U.S. Provisional Patent Application No. 62/278,109, filed on Jan.13, 2016 and titled “Electronic Roundsling Inspection, Load Monitoringand Warning System,” the entire contents of which are incorporatedherein by reference in their entirety.

BACKGROUND OF THE INVENTION

Preferred embodiments of the present invention relate generally to asystem and method for warning when a roundsling is loaded beyond itsrated capacity, load limit or is potentially nearing failure. Preferredembodiments of the invention also relate to a system and method formonitoring loads applied to a roundsling in real time.

Industrial slings are typically constructed of metals or syntheticmaterials. Wire rope slings are commonly made of a plurality of metalstrands twisted together and secured by large metal sleeves or collars.Synthetic slings are usually comprised of a lifting core made of strandsof synthetic fiber and an outer cover that protects the core. Thestrands of the core are typically inserted in a generally parallelorientation to the other strands within the core, but may also betwisted as they are inserted into the cover, as is described inSlingmax's U.S. Pat. No. 7,926,859, which is incorporated herein byreference in its entirety. Synthetic slings provide weight, strength andother advantages over wire rope slings. One popular design of syntheticslings is a roundsling in which the lifting core forms a continuous loopand the sling has a circular or oval-shaped appearance.

Modern industrial slings may experience failure and loss of a loadcaused by the sling breaking or failing, for example, because the slingis fatigued, over-stretched or over-loaded during a current or previoususe. When subjected to an overload condition in excess of its ratedcapacity, a roundsling may be permanently damaged and/or deformed if theload stretches the fibers of the load bearing core material beyond theirrated strength. When a synthetic fiber sling is overloaded beyond itstensile strength or weight-lifting capacity, it is considered to bedamaged and may never return to its normal strength and load bearingcapacity. Detection of such overloading conditions can be difficult tovisually or otherwise inspect or determine during field use.

Slings are generally provided with specified load capacity (ratedcapacity), which is a load over which the particular sling should not beloaded. The rated capacity also provides guidance to users regarding therated or safe lifting capacity of the sling. Nevertheless, this capacityis sometimes exceeded, either accidentally, by unexpected shock loading,or by users engaging in unsafe shortcuts during rigging and use of thesling. In addition, as the sling is used, it may become subject toabrasion, cuts or other environmental degradation to its fibers, whichalso weaken the working load limit, actual capacity and tensile strengthof the sling and potentially negatively impact the rated capacity.Environmental factors that may weaken the working load limit, capacityand tensile strength of the sling include poor maintenance, ultravioletradiation exposure, bending, kinks, knots, wear, fatigue, retention ofwater, temperature, and other related environmental factors.Individually or cumulatively, such conditions may lead to unexpectedfailure of the sling during use. It is, therefore, desirable to measureand record the loads that are applied to a sling every time the sling isused for lifting.

There are no methods known in the art for continuous, direct measurementof loads on either a wire rope or synthetic sling during industrial orfield-use settings. Current methods rely on detecting only an overloadcondition or indirect measurements of loads, e.g., using load cells atattachment points or related measurement techniques. Depending on therigging configuration, these indirect measurements may providemisleading information on direct loads applied to each independent slingthat is used in a lifting job.

Often, over-load, fatigue, or damage to the sling materials are notreadily apparent as the result of visual inspection, particularly giventhe large size or length of a particular sling, or because theload-bearing core is hidden inside the outer cover. If a roundsling isfatigued or structurally changed, the sling may no longer be able tolift a load according to its maximum rated load capacity or its loadlimit. These fatigue or structurally weakened conditions may become athreat to operators and riggers using the damaged sling.

A commercially available roundsling may include a pre-failure indicator.An example of such a pre-failure warning indicator is described in U.S.Pat. No. 7,661,737, the contents of which are incorporated herein byreference in their entirety. Such pre-failure indicators are designed toproduce a visible sign of overload when the sling is overloaded beyondits rated capacity, but below its breaking strength. These pre-failurewarning indicators do not determine the exact load imparted on the slingduring loading, but only provide an indication that the sling was loadedbeyond its rated capacity. In addition, depending on the riggingconfiguration and location of the sling or pre-failure indicator on thesling, it may be difficult for operators or riggers to visually identifythe activation of the pre-failure indicators during the liftingoperation. The inability to immediately identify the overloadingcondition might result in unsafe lifting operations continuing until theriggers inspect the roundsling after the lifting operation is completed.

There is a need in the art of rigging and sling inspection forconsistent and reliable sling pre-failure indication. In addition, thereis a need to identify structurally sound slings that have usefuloperational life even after their initially predicted lifetime. There isalso a need to provide for structural health monitoring of the sling bymonitoring the loads applied to the sling and the environmental exposureof the sling during operation to determine the state of the systemhealth during the useful life or to more accurately predict the usefullife of the sling. Finally, there is a need to measure loads that areimparted on slings in real time during lifting operations and to recordand store loading information for individual slings over their lifetimeto provide accurate and predictable useful life predictions for theslings. An advanced warning that a sling is near its breaking pointprovides operators of the sling with an opportunity to take correctiveaction. In addition, advanced warning of the structural capacity of thesling by monitoring and/or predicting the structural health of the slingcan extend the lifetime of the sling, thereby reducing the necessity forcostly and unnecessary replacement of the sling. Further, knowing thelifetime loading, environmental factors and overload history of aparticular sling allows riggers to identify and select the safest andmost appropriate equipment for each rigging task.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary, as well as the following detailed description ofthe invention, will be better understood when read in conjunction withthe appended drawings. For the purpose of illustrating the preferredinvention, there is shown in the drawings an embodiment which ispresently preferred. It should be understood, however, that theinvention is not limited to the precise arrangements andinstrumentalities shown. In the drawings:

FIG. 1 is a top perspective view of an exemplary roundsling for use withthe electronic overload inspection and warning system in accordance witha preferred embodiment of the present invention;

FIG. 2 is a cross-sectional view of the exemplary roundsling of FIG. 1,taken along section line 2-2;

FIG. 3 is a schematic diagram of the electronic overload inspection andwarning system in accordance with the preferred embodiment of thepresent invention;

FIG. 4 is a front elevational, schematic view of the electronic overloadinspection and warning system of FIG. 3, installed in a roundsling withportions of the roundsling being transparent for clarity;

FIG. 5 is a top plan view of a first preferred carrier plate of theelectronic overload inspection and warning system of FIG. 1, wherein thecarrier plate is attached to strands of the roundsling and includes astrain gauge mounted thereto;

FIG. 5A is a top perspective view of a second preferred carrier plate ofthe preferred electronic overload inspection and warning system of FIG.1;

FIG. 5B is a side elevational view of the carrier plate of FIG. 5A;

FIG. 5C is a top plan view of the carrier plate of FIG. 5A;

FIG. 5D is a front elevational view of the carrier plate of FIG. 5A;

FIG. 6 is a top perspective view of a third preferred carrier plate ofthe preferred electronic overload inspection and warning system of FIG.1;

FIG. 6A is a top plan view of the carrier plate of FIG. 6;

FIG. 6B is a side elevational view of the carrier plate of FIG. 6;

FIG. 6C is a cross-sectional view of the carrier plate of FIG. 6, takenalong line 6C-6C of FIG. 6A;

FIG. 7A is a top perspective view of a fourth preferred carrier plate ofthe preferred electronic overload inspection and warning system of FIG.1;

FIG. 7B is a top perspective view of the carrier plate of FIG. 7Apartially enclosed in a housing in accordance with a preferredembodiment of the present invention;

FIG. 7C is a top perspective view of the carrier plate of FIG. 7Apartially enclosed in the housing of FIG. 7B, wherein a top housingportion is shown as partially transparent; and

FIG. 8 is a side elevational view of a failure indicator system inaccordance with a preferred embodiment of the present invention.

DESCRIPTION OF THE DISCLOSURE

Certain terminology is used in the following description for convenienceonly and is not limiting. The words “lower,” “bottom,” “upper” and “top”designate directions in the drawings to which reference is made. Thewords “inwardly,” “outwardly,” “upwardly” and “downwardly” refer todirections toward and away from, respectively, the geometric center ofthe roundsling and related components of the preferred systems, anddesignated parts thereof, in accordance with the present disclosure.Unless specifically set forth herein, the terms “a,” “an” and “the” arenot limited to one element, but instead should be read as meaning “atleast one.” The terminology includes the words noted above, derivativesthereof and words of similar import.

It should also be understood that the terms “about,” “approximately,”“generally,” “substantially” and like terms, used herein when referringto a dimension or characteristic of a component of the invention,indicate that the described dimension/characteristic is not a strictboundary or parameter and does not exclude minor variations therefromthat are functionally the same or similar, as would be understood by onehaving ordinary skill in the art. At a minimum, such references thatinclude a numerical parameter would include variations that, usingmathematical and industrial principles accepted in the art (e.g.,rounding, measurement or other systematic errors, manufacturingtolerances, etc.), would not vary the least significant digit.

Referring to the drawings in detail, wherein like numerals indicate likeelements throughout, there is shown in FIGS. 1-4 an electronic overloadinspection and warning system, generally designated 10, for roundslings50 in accordance with a preferred embodiment of the present invention.

The roundsling 50 preferably includes a load-bearing core 52 and a cover56 that surrounds and protects the load-bearing core 52. The core 52 maybe comprised of a plurality of strands 54 (FIG. 2) that may befabricated from any suitable material, including metal or syntheticpolymers or composite materials. The core 52 may comprise one or morenatural or synthetic materials, such as polyester, polyethylene, nylon,K-Spec® (Slingmax®, Inc., comprising a proprietary blend of fibers),high-modulus polyethylene (“HMPE”), liquid crystal polymer (“LCP”),aramid, para-aramid, or other suitable synthetic material. The materialof the core 52 may relate to the maximum weight the sling 50 is designedto lift, and the environment in which the sling 50 is preferably used.In general, synthetic strands 54 have a high lifting and break strength,lighter weight, high temperature resistance and high durability,compared to wire rope or metal chain slings. In addition, the cover 56preferably limits damage to the core 52 and surfaces of the objects thatare being lifted and related equipment that comes into contact with thecover 56 during use.

The core 52 is preferably positioned within the protective cover 56. Thecore 52 generally bears substantially the entire weight of the load tobe lifted. The cover 56 generally prevents physical damage to the core52, for example from abrasion, and sharp edges on the load, as well asprotects the core 52 from exposure to harsh environmental conditionssuch as heat, humidity, ultraviolet light, corrosive chemicals, gaseousmaterials, or other environmental conditions that may damage or weakenthe core 52 materials.

In the preferred embodiment, the core 52 includes a first core 53 a anda second core 53 b positioned within the cover 56. The first and secondcores 53 a, 53 b are preferably positioned side-by-side within the cover56 and provide twin load paths to carry loading on the roundsling 50.The roundsling 50 is not limited to including the two cores 53 a, 53 band may be constructed with a single core or more than two cores withoutsignificantly impacting the function of the roundsling 50. The first andsecond cores 53 a, 53 b are preferably positioned within side-by-sidechambers 55 a, 55 b defined by the cover 56, with the cover 56 connectedtherebetween by a fastening mechanism 57. In the preferred embodiment,the fastening mechanism 57 is comprised of stitching that connectsopposing sides of the cover 56 to define the chambers 55 a, 55 b. Theroundsling 50 is not limited to inclusion of the fastening mechanism 57or to the fastening mechanism being comprised of stitching and may notinclude the fastening mechanism 57 or the fastening mechanism 57 may beconstructed of alternative mechanisms, such as adhesive bonding,integral forming, clamping or other mechanisms that facilitate formingof the first and second chamber 55 a, 55 b within the cover 56.

The electronic overload inspection and warning system 10 preferablyincludes a wireless sensor system 12 installed within or on theroundsling 50, a wireless base station 14, capable of communicating withmultiple roundslings 50 deployed in the field, and an operator terminal16 (shown schematically in FIG. 3) usable by an operator to monitor andvisualize loads on the multiple roundslings 50 deployed in the field andpreferably displaying loading information and overload indications.Communication between the sensor system 12 and the base station 14preferably provides real-time, continuous loading information for eachof the multiple roundslings 50 deployed in the field.

In the preferred embodiment, and as shown schematically in FIG. 3, thesensor system 12 includes a strain gauge 18 for measuring strain(elongation) of each of the roundslings 50 of the multiple roundslings50 deployed in the field. For example, the strain gauge 18 may be atwo-axis strain gauge for measuring both axial and transverse loads. Thestrain gauge 18 may be configured to address temperature compensation,as is generally known in the art. The strain gauge 18 may also becomprised of a plurality of strain gauges 18 that measure strain invarious directions and orientations, such as a four gauge bridge orWheatstone Bridge configuration. The strain gauge 18 may further becomprised of a plurality of gauges positioned for measuring strain andstress on the cores 53 a, 53 b and cover 56. The strain gauge 18 ispreferably battery operated, and is preferably powered by a batterysource 19 providing a minimum one year battery life, but is not solimited. The strain gauge 18 may be configured to have nearly anyduration of battery life, such as about two to three years of batterylife. The battery 19 may be comprised of, for example, a one thousandmilliampere-hour (1000 mAh) primary (non-rechargeable) lithium battery19 (e.g., Panasonic CR 2477). In addition, the battery 19 may beconfigured for recharging during deployment of the roundsling 50. Thebattery 19 may, for example, be comprised of an energy-harvestingbattery 19 that recharges when subjected to vibrations, such as when theroundsling 50 is in use or being rigged. Alternatively, the battery 19may be comprised of a solar rechargeable battery 19 that is connected toa solar recharging strip 19 a (FIG. 1) mounted to an external surface ofthe roundsling 50. When the solar recharging strip 19 a is exposed tosolar energy during deployment, the strip 19 a preferably provideselectrical recharging energy to the battery 19 to limit the return ofthe roundsling 50 to the manufacturer for replacement of the battery 19and, therefore, potentially extended operating life for the roundsling50 before the roundsling 50 is returned to the manufacturer or repaired.The battery 19 may alternatively be comprised of a piezoelectric powercell that generates power or electricity when under load and also storesthe generated electricity well beyond the time of generation. Such apiezoelectric power cell-type battery 19 may be configured with theroundsling 50 to generate electricity when the roundsling 50 is loadedand store the electric energy to power the strain gauge 18, transmitter20 and any additional components of the preferred roundsling 50. Thestrain gauge 18 is preferably, electrically connected to a wirelesstransmitter 20. For example, without limitation, the wirelesstransmitter 20 may be a Lord MicroStrain SG-Link-OEM-LXRS wireless2-channel analog input sensor node. Optionally, the transmitter 20 mayhave an external whip antenna (not shown).

In the preferred embodiment, the batteries 19 are removable andreplaceable from the roundsling 50, such that the batteries 19 may beremoved and replaced at predetermined intervals. The batteries 19 may beremovable and replaceable by the operators or users or may be returnedto the manufacturer for removal, replacement and, preferably,maintenance and inspection of the roundsling 50. The manufacturer, forexample, may recalibrate the strain gauge 18 when the roundsling 50 isreturned for replacement of the battery 19, may conduct visualinspection of the roundsling 50, may test and calibrate an environmentalmonitoring chip 30, which is described in greater detail below, mayqualify or re-qualify the loading recommendations, rated capacity, loadcapacity or capability of the roundsling 50 and may otherwise inspectand maintain the roundsling 50 for return to the operator.

The strain gauges 18 are preferably bonded to rigid, flat (orgently-curved) surfaces in order to accurately measure strain (orelongation). Prior to the preferred invention, it has been difficult tomeasure strain directly on roundslings 50, because it is difficult tonearly impossible to reliably adhere strain gauges 18 on either fibersor strands of the roundslings 50 or twisted steel ropes of wire ropes.

The sensor system 12 of the preferred embodiment also includes theenvironmental monitoring chip 30 that is preferably powered by thebattery 19 and is in communication with the transmitter 20. Theenvironmental monitoring chip 30 is preferably configured to monitorchanges to the roundsling 50 or geometric properties of the roundsling50, including changes to the environmental boundary conditions whereinthe roundsling 50 is deployed, which may adversely impact theroundsling's performance. The environmental monitoring chip 30 may sensevarious features of the roundsling 50 and its operating environmentduring use, such as temperature, humidity, pH, sunlight, ultravioletradiation, chemical presence and exposure, vibration, conductivity,moisture, and related features of the roundsling 50 and its environmentthat may impact the roundsling's performance, load rating or usefullife. The environmental monitoring chip 30 may also sense the presenceof hazardous chemicals or gases near or around the roundsling 50, suchas combustible chemicals or gases, radiation, chlorine, carbon monoxide,reduced levels of oxygen, high levels of airborne contaminants, organicvapors, asbestos, metals, pesticides, immediately dangerous to life orhealth chemical or gas conditions, carcinogens, toxins, irritants,corrosives, sensitizers, hepatotoxins, nephrotoxins, neurotoxins as wellas agents that act on the hematopoietic systems or damage the lungs,skin, eyes, or mucous membranes and other related or similar hazardouschemicals or gases. In addition to monitoring environmental conditionsthat may negatively impact the roundsling 50, the environmentalmonitoring chip 30 could act as a warning for conditions that may beunsafe for the people, operators or technicians using the roundslings50. These conditions could include toxic, flammable, or explosivechemicals and low oxygen levels.

The environmental monitoring chip 30 preferably periodically sensesthese features and transmits the features to the transmitter 20, whichsubsequently transmits the information to the wireless base station 14.The plurality of sensed features, including the loading featuresdetected by the strain gauge 18 are utilized to consider the totality ofexposure of the roundsling 50 to loads and environment during use, tostatistically analyze the sensed features and preferably determine thecurrent state of the roundsling 50. The statistical analysis ispreferably able to predict the ability of the specific roundsling 50 toperform its intended function in light of aging and degradationresulting from use of the roundsling 50 and the environment in which theroundsling 50 is used. For example, the history of loading andenvironment of a plurality of roundslings 50 available for use by anoperator may be considered based not only on their ratings developedwhen they shipped in new condition from the factory, but also followingtheir own unique loading and environmental histories. Such analysis andhistorical consideration may permit roundslings 50 having histories oflight loads in favorable environmental conditions to have an extendedlife and limit the need to dispose and replace such roundslings 50before their real useful life is attained. Likewise, a roundsling 50that is exposed to extreme loading and unfavorable environmentalconditions may be removed from service prior to a standard usefullifetime based on its unique loading and environmental history, whichcan improve safety of rigging or lifts involving such roundsling 50. Thefrequency of sampling using the environmental monitoring chip 30 may bestandardized such that the chip 30 collects specific features after apredetermined time period or may be variable, such as the chip 30sampling particular features more frequently when the roundsling 50 isloaded and less frequently when the roundsling 50 is unloaded.Furthermore, the environmental monitoring chip 30 may collect and storedata from its sensors for an arbitrary period of time, and it maytransmit all of the stored data or merely a fraction of the stored datato the base station 14.

The environmental monitoring chip 30 of the preferred embodiment may becomprised of a System-on-a-Chip (“SoC”) integrated circuit comprised ofvarious sensors, a processing unit, and a data storage unit. Thepreferred SoC chip 30 may be mounted to the roundsling 50 without takingsignificant space in the roundsling 50 and is preferably configured tomeasure various features of the roundsling 50 and the associated workingenvironment to transmit data to the base station 14 for environmentaland load monitoring purposes.

Referring to FIGS. 5-5D, in preferred embodiments, a carrier element orplate 26 is mounted in series (in line) with the load-bearing strands 54of the lifting core 52. In these preferred embodiments, the carrierplate 26 is inserted between two ends of a load-bearing strand 54 of thecore 52 (shown schematically in FIG. 5). FIG. 5 shows a first preferredembodiment of the carrier plate 26 having a substantially block-shapeand FIGS. 5A-5D show a second preferred embodiment of the carrier plate26 having a cylindrical or pill-shape, although both the first andsecond preferred embodiments are identified with like reference numeralsindicating similar features. The carrier plate 26 is preferably attachedto the load-bearing strand 54 by inserting a first end 54 a of thestrand 54 through a first hole 62 a in the carrier plate 26 and making afirst knot 64 a to secure the first end 54 a to the first hole 62 a andthe carrier element 26 and subsequently inserting a second end 54 b ofthe strand 54 through a second hole 62 b in the carrier plate 26 andmaking a second knot 64 b to secure the second end 54 b to the secondhole 62 b and the carrier element 26. The first end 54 a and the secondend 54 b of the strand 54 are not necessarily secured to the first andsecond holes 62 a, 62 b of the carrier element 26 by the knots 64 a, 64b and may be otherwise secured to the carrier element 26, such that thecarrier element 26 is subjected to nearly the same loads as are carriedby the strand 54 during use. For example, the first and second ends 54a, 54 b of the strand 54 may be clamped, fastened, adhesively bonded orotherwise secured to the carrier plate 26 in a manner that willwithstand the typical operating conditions of the roundsling 50 and havethe ability to carry the loads typically encountered by the roundsling50 and the individual strands 54. In addition, the carrier element 26 isnot limited to having the first and second holes 62 a, 62 b for securingto the first and second ends 54 a, 54 b of the strand 54 and may beconfigured as an alternate fastening mechanism, such as a clamp orfastener or may be otherwise designed and configured to accept securingof the first and second ends 54 a, 54 b thereto.

By virtue of being in series (in line) with the load path of theindividual strand 54, the carrier plate 26 preferably carriessubstantially the same load as the individual strand 54 and the otherstrands 54 in the load-bearing core 52. In the preferred embodiment, thecarrier plate 26 has a flat (or gently-curved) surface or receptacle 66where the strain gauge 18 is preferably securely bonded to the carrierplate or element 26. The carrier plate 26 may be constructed of nearlyany rigid substance that is able to take on the general size and shapeof the carrier element 26, is able to withstand the normal operatingconditions of the carrier element 26 and is suitable for the straincharacteristics of the strain gauge 18, such as, but not limited toaluminum, steel, stainless steel, 316 stainless steel, composite, or amultitude of other substantially rigid materials. Electrical leads 60preferably carry the strain signal out of the strain gauge 18 and to thetransmitter 20 for signal processing and subsequent transmission to thebase station 14.

In the second preferred embodiment, the carrier plate 26 has asubstantially cylindrical shape, with the receptacle 66 formed on itssurface in order to attach the strain gauge 18, such that the straingauge 18 is oriented to measure strain substantially along alongitudinal axis 25 of the carrier plate 26. The carrier plate 26 isnot limited to having substantially cylindrical configurations and maybe formed in a multitude of cross-sectional shapes, including circular,rectangular, square, oval, triangular, tubular, hollow cylinder andother shapes that are able to withstand the ordinary operatingconditions of the roundsling 50, attach to the first and second ends 54a, 54 b of the strand 54, carry the load imparted from the strand 54 andeffectively mount the strain gauge 18 during normal operating conditionsof the roundsling 50. The strain gauge 18 may be bonded to thereceptacle area or surface 66 on the carrier plate 26 or may be mountedat alternative locations on the carrier element 26. Depending on theshape and curvature of the carrier plate 26, the receptacle area 66 maybe flat or gently-curved, but is not so limited and may have nearly anysize and shape that is able to withstand the normal operating conditionsof the carrier element 26 and perform the typical functions of thecarrier element 26. Furthermore, depending on the shape and curvature ofthe carrier plate 26, there may not be a need for a distinct receptaclearea 66. For instance, on a substantially flat, rectangular, boxy orparallelepiped carrier plate 26, the strain gauge 18 may be bonded toany region or surface of the carrier plate 26 that is able to receivethe strain gauge 18 without the need for a distinct receptacle 66.

In the second preferred embodiment, the carrier element or plate 26 hasa length L and a diameter D with substantially hemispherical endspositioned along the longitudinal axis 25. The length L and diameter Dare preferably sized to correspond to the general size of the individualstrand 54 to which the carrier element 26 is connected, but are not solimited. In the preferred embodiment, the carrier element 26 may have alength of approximately two to three inches (2-3″) and a diameter ofapproximately one-half to one inch (½-1″), but is not so limited. Thereceptacle area 66 of the preferred embodiments has a receptacle lengthx of approximately one-quarter to three-quarters of an inch (¼-¾″) and areceptacle width y of approximately one-quarter to one-half inch (¼-½″),but is not so limited and may have nearly any size and shape that isable to accept the strain gauge 18 or may be excluded from the carrierelement 26 when the strain gauge 18 is mounted directly to the side ofthe carrier element 26, as is described above. The first and secondholes 62 a, 62 b of the first preferred embodiment have a substantiallyconsistent hole diameter d (not labeled) of approximately three-eighthsinches (⅜″), but are not so limited and may have nearly any size, shapeor configuration to accept the ends 54 a, 54 b of the strand 54 or maybe excluded from the carrier plate 26, as was described above.Alternatively, in the second preferred embodiment, the holes 62 a, 62 bhave a substantially oblong-shape, with a major length H₁ ofapproximately one-quarter to one-third of an inch (¼-⅓″) and a minorlength H₂ of approximately one-eighth to three-eighths of an inch(⅛-⅜″). The holes 62 a, 62 b of the second preferred embodiment are notlimited to being substantially oblong-shaped and may have asubstantially constant diameter, may be eliminated from the carrierplate 26 or may take on an alternative size and shape that is able toaccept the ends 54 a, 54 b of the strand 54 and withstand the normaloperating conditions of the carrier element 26.

Referring to FIGS. 6-6C, in a third preferred embodiment, a carrierelement 126, having similar function and features to the first andsecond preferred carrier elements 26, may also be mounted in series (inline) with the load bearing strands of the lifting core 52. The carrierelement 126 of the third preferred embodiment is described herein withlike reference numerals indicating like features and a “1” prefixdistinguishing the third preferred carrier element 126 from the firstand second preferred carrier elements 26. The lifting core 52 ispreferably connected to the carrier element 126 at first and secondholes 162 a, 162 b such that the carrier element 126 carriessubstantially the same load as the individual strands 54 during use. Areceptacle 166 is preferably formed in the carrier element 126 and issized and configured to receive a strain gauge (not shown) that measuresload and strain on the carrier element 126. In the third preferredembodiment the receptacle 166 is inset into the surface of the carrierelements 126, bus is not so limited and may be substantially flush withthe surfaces of the carrier element 126 and may be located at differentlocations on the carrier element 126. The carrier element 126 ispreferably constructed of a relatively strong and stiff metallicmaterial, such as steel, stainless steel, 316 stainless steel, aluminum,7075 aluminum or other relatively strong and stiff materials that areable to take on the general size and shape of the carrier element 126and withstand the normal operation conditions of the carrier element126, such as a composite material.

In the third preferred embodiment, the carrier element 126 has asubstantially dog bone-shape or dumbbell-shape with relatively widefirst and second ends 126 a, 126 b and a relatively narrow centralsection 126 c. The carrier element 126 has an overall carrier length Z,a central section length z, a major width W measured as the diameter ofthe first and second ends 126 a, 126 b in the plan view, a minor width wof the central section 126 c, a major thickness T measured at the firstand second ends 126 a, 126 b and a minor thickness t measured in thecentral section 126 c proximate the receptacle 166. In the thirdpreferred embodiment, the overall carrier length Z is approximately fourto five inches (4-5″), preferably four and three-quarters inches (4¾″),the central section length z is approximately two to three inches(2-3″), preferably two and one-quarter inches (2 V), the major width Wis approximately one to one and one-half inches (1-1½″), preferably oneand one-quarter inches (1¼″), the minor width w is approximatelyone-half to three-quarters inches (½-¾″), preferably six tenths inches(0.6″), the major thickness T is approximately one-quarter to one-halfinches (¼-½″) and the minor thickness t is approximately one-tenth toone-quarter inches ( 1/10-¼″), preferably one-sixth of an inch (⅙″).These dimensions for the third preferred carrier element 126 are notlimiting and the carrier element 126 may be sized and configured innearly any manner that permits engagement with the core strand 54 suchthat the carrier element 126 carries the load of the core strand 54during use, is able to be mounted to the core strand 54 and withstandsthe normal operating conditions of the carrier element 126, as isdescribed herein. The carrier element 126 also preferably has curved orarcuate surfaces when transitioning between its various surfaces, suchas the sidewalls of the first and second holes 162 a, 162 b, theexternal surfaces of the first and second ends 126 a, 126 b and whentransitioning between the first and second ends 126 a, 126 b and thecentral section 126 c. These arcuate and curved surfaces are preferablydesigned and configured to limit damage to the core strands 54 and otherportions of the core 52 and cover 56 if these elements rub, slide or arepositioned against the carrier element 126. In the third preferredembodiment, the first and second holes 162 a, 162 b have inner curvessurfaces that form a substantially hyperboloid-shape to facilitateengagement with the core strands 54, but are not so limited and may havenearly any size or shape that is able to accept the core strands 54 orengage with the core strands 54, preferably an arcuate or curvedsurface. In addition, the first and second holes 162 a, 162 b may havean oval-shape, similar to the first and second holes 62 a, 62 b of thesecond preferred embodiment.

Referring to FIG. 7A, a fourth preferred carrier element 126′ has asimilar construction to the third preferred carrier element 126 and likereference numbers are utilized to identify like features of the fourthpreferred carrier element 126′ with a prime symbol (′) utilized todistinguish the fourth preferred embodiment from the third preferredembodiment. The fourth preferred carrier element 126′ has slightlysquared edges or corners of the first and second ends 126 a′, 126 b′ incomparison to the more rounded edges of the third preferred embodimentand does not include an indentation in the central section 126 c′ forreceipt of the strain gauge. The fourth preferred carrier element 126′is otherwise substantially constructed in the same manner as the thirdpreferred carrier element 126.

The fourth preferred carrier element 126′ preferably includes sealingrings 140 positioned on or overmolded onto the central section 126 c′proximate opposite ends of the central section 126 c′ near the first andsecond ends 126 a′, 126 b′. The sealing rings 140 are preferablyconstructed of a rubber-like material that permits sealing of thecentral section 126 c′ with a housing 75 that may be engaged to thecarrier element 126′. The housing 75 provides protection for the straingauge 18 and other electronic equipment of the electronic overloadinspection and warning system 10. The electronic overload inspection andwarning system 10 is not limited to inclusion of the sealing rings 140for sealing the housing 75 relative to the carrier elements 26, 126,126′ and the housing 75 and carrier elements 26, 126, 126′ may beotherwise designed and configured to protect and seal the electroniccomponents of the electronic overload inspection and warning system 10during operation, such as by overmolding a polymeric material or filmover the components and the carrier elements 26, 126, 126′ or otherwisecovering and protecting the electronic components.

Referring to FIGS. 5-7C, in the preferred embodiments, the carrierelement 26, 126, 126′ is at least partially enclosed by the housing 75,particularly over the strain gauge 18. The housing 75 preferablyincludes a top housing portion 75 a and a bottom housing portion 75 b.The top and bottom housing portions 75 a, 75 b are preferablyconstructed of a polymeric material, such as Acrylonitrile ButadieneStyrene (“ABS”), but are not so limited and may be constructed of nearlyany polymeric, metallic, wooden or other structural material that isable to take on the general size and shape of the housing 75, performthe preferred functions of the housing 75 and withstand the normaloperating conditions of the housing 75. The top and bottom housingportions 75 a, 75 b preferably snap together over the central section126 c, 126 c′ of the carrier elements 26, 126, 126′ and engage thesealing rings 140 to inhibit flow of external liquid and air into thehousing 75. The top and bottom housing portions 75 a, 75 b arepreferably force snapped, welded or bonded together such that detachingthe top housing portion 75 a from the bottom housing portion 75 b from aworking configuration is difficult for a user. Preferably, during fielduse, the housing 75 is not opened or separated and is only opened whenreturned for inspection and maintenance to the manufacturer. The housing75 is not limited to being difficult to open for a user and may beconfigured for opening and closing by a user for inspection, maintenanceor other operations.

The preferred housing 75 includes a battery 76 and a circuit board 78enclosed therein. The battery 76 preferably provides power for thecircuit board 78, which may include at least the wireless transmitter 20and a controller (not shown). The housing 75 provides protection andstructural support for the wireless transmitter and controller. Thehousing 75 is not limited to including the wireless transmitter 20,battery 76 and circuit board 78 therein, but inclusion of theseelectronic components in the housing 75 is preferred to provideenvironmental protection and structural support for these components.

Referring to FIGS. 1-8, the wireless base station 14 preferably includesa wireless receiver 22, for wirelessly receiving data from the wirelesstransmitter 20. For example, the preferred receiver 22 may be a LordMicroStrain WSDA-BASE-104 USB gateway node, but is not so limited andmay be comprised of nearly any receiver 22 that is able to wirelesslyreceive data from the wireless transmitter 20, withstand the normaloperating conditions of the receiver 22 and otherwise perform thepreferred functions of the receiver 22, as is described herein. Thewireless transmitters 20 and receiver 22 preferably exhibit a minimum ofabout a one hundred fifty foot (150′) communication range, andpreferably, approximately a five hundred foot (500′) communicationrange, but are not so limited and may have a shorter or longercommunication range. For instance, using cellular communicationprotocols, the wireless transmitter 20 and receiver 22 may communicateat nearly any range, even across a continent or around the earth. Inaddition, the preferred system is not limited to configurationsincluding the wireless transmitters 20 and receiver 22 by hard wiringthe strain gauges 18 directly to the base station 14. Wireless signaltransmission is preferred for the system, however, particularly when thebase station 14 is monitoring loads on multiple roundslings 50.

The receiver 22 is preferably electrically connected to a computingdevice 24 in the operator terminal 16, such as, for example, a computer,tablet, smart phone, or the like, capable of computing and manipulatingthe data received, visualizing and monitoring the sling loads, anddisplaying overload indicators. In one embodiment, the computing device24 is a Windows laptop or PC having a data acquisition and deviceprogramming software (e.g., LabView or the like) and offline dataanalysis software (e.g., Microsoft Excel or the like). The computingdevice 24 is preferably capable of statistically analyzing the acquireddata from the strain gauge 18 and the environmental monitoring chip 30to determine a predicted current state or health of the roundsling 50based on the various sensed features of the roundsling 50 and itsworking environment. The computing device 24 also preferably has atleast one connection port, e.g., a USB or other serial or parallel port,for connecting with the receiver 22, but is not so limited.

At a minimum, the computing device 24 preferably calculates the stresson the roundsling 50 according to the strain data received from thewireless sensor system 12 of one or more of the roundslings 50 and themodulus of elasticity of the respective carrier plate material(Stress=Strain*Modulus of Elasticity). The receiver 22 may be configuredto communicate with multiple transmitters 20 deployed in the fieldsimultaneously (three sensor systems 12 shown in FIG. 3 for illustrativepurposes), e.g., three roundslings 50, and, therefore, the multipleroundslings 50 may be monitored simultaneously from the base station 14.The receiver 22 may alternatively be configured to communicate with asingle transmitter 20 associated with a single roundsling 50, tworoundslings 50 or many more than three roundslings 50. The forceimparted on the roundsling 50 by the load may be estimated bymultiplying the measured stress with the surface area of the carrierelement 26. The force may then be converted to a weight estimate for theload using physics calculations are generally known by those havingordinary skill in the art.

In order to account for differences in construction in each sling, asystem of calibration can be employed to compensate for differences inthe tension applied to the carrier element 26. The roundsling 50 may beplaced in a tensile tester in line with a calibrated load cell and putunder a series of known loads. These loads may be entered into acomputer that is wirelessly communicating with the wireless transmitter20. By matching the signal from the strain gauge 18 with the known load,a calibration curve can be generated that allows for accurate readingsof loads in use. In order to simplify the process a calibration mode canbe included with the computing device 24. The mode can prompt theoperator through the process of calibrating and automatically load thetransmitter with the final calibration information. In addition, whenthe roundsling 50 is returned for maintenance or on a predeterminedschedule, the roundsling may be recalibrated in the same manner and thefinal calibration information can be reloaded to compensate for anychanges in the original calibration.

The strain gauge 18 is preferably of compact size, in order touniversally fit in substantially any size roundsling 50. As shown inFIG. 4, the strain gauge 18 may be installed on the carrier plate orelement 26 and attached between the two ends 54 a, 54 b of the strand 54of the core 52. The carrier plate 26 of the first preferred embodimentis utilized as an example in the following description and the carrierplates 26, 126, 126′ of the second, third and fourth preferredembodiments may also be utilized with the roundsling 50 in a similar orthe same manner as is described below. The carrier plate 26 ispreferably placed inside of the protective cover 56, thereby protectingthe gauge 18 from environmental hazards, such as water, oil orelectromagnetic (“EM”) radiation. In one preferred embodiment, thewireless transmitter 20 is also installed in a protective pocketattached to the sling cover 56, e.g., in the form of a short tail. Thetail may be of a different color material in order to indicate thepresence of sensitive electronics inside. Electrical connections withinthe roundsling 50 are preferably protected at least by the protectivecover 56 and may be further protected by additional covers, materials orplacement, such as centrally within the core strands 54. The carrierplate 26, strain gauge 18, wireless transmitter 20 and relatedcomponents are not limited to being mounted within the cover 56, but arepreferably mounted therein for connection to the strands 54 and toprovide protection of these components during field use. For example, inthe fourth preferred embodiment, the circuit board 78, battery 76 andstrain gauge 18 are mounted within the housing 75 to provide structuraland environmental protection for the electronic components of theelectronic overload inspection and warning system 10.

In the preferred embodiments, the electronic overload inspection andwarning system 10 is battery-powered and power-saving measures arepreferably utilized in order to extend battery life. The electronicoverload inspection and warning system 10 may alternatively be poweredusing other means including household electricity or an electricalgenerator, thus limiting the preference for power-saving measures. Inthe preferred embodiment, prior to loading the roundsling 50, thetransmitters 20 and receiver 22 are powered on. Upon powering, thetransmitters 20 and receiver 22 are preferably left in low-power sleepmode for battery preservation. In sleep mode, the transmitters 20 andreceiver 22 periodically wake up and wait for wake signals from the basestation 14. When a wake signal is received, the transmitters 20 andreceiver 22 preferably enter into the low duty cycle mode withevent-based sampling. In this preferred low duty cycle mode, thereceiver 20 starts sampling the transmitters 20 at a low frequency(e.g., 1 Hz) but only transmits data to the computing device 24 if acertain, predetermined event takes place. In the case of the slingapplication, the expected event is the measurement of a non-zero load onthe strain gauge 18, which is preferably transmitted from thetransmitter 20 to the receiver 22.

When the roundsling 50 is loaded and the wake signal is sent from thetransmitter 20 to the receiver 22, the strain gauge 18 preferablymeasures elongation of the carrier plate 26, 126, 126′. The measureddata and any overload indicator integrity data is preferably, wirelesslytransmitted from the transmitter 20 to the receiver 22 at presetintervals. The receiver 22 relays the data to the computing device 24for additional data processing, visualization, alerting, and/or storage.Trigger signals, e.g., a stress value that is greater than an associatedmaximum safe stress value, preferably induce an alarm by the operatorterminal 16, e.g., an audible alarm, a written message, a text messageto the operator's phone, a visual alarm, a signal to the equipment tolock operation, or the like. As should be understood, the receiver 22may receive data from multiple transmitters 20 deployed in multipleroundslings 50. Data calculated by, and displayed on, the computingdevice 24 indicates the respective roundsling 50 and the associatedstress and/or strain associated with the roundslings 50.

In addition to the wake signal, the base station 14 preferably pingseach transmitter 20 at regular intervals in order to confirm the sensorsystem 12 is available and operational. The transmitters 20 and receiver22 also preferably return into low-power sleep mode after apredetermined period of inactivity, such as one to five hours (1-5 hrs).

In addition to being employed alone, the electronic overload inspectionand warning system 10 may also be employed to function with otherpre-failure warning indicators, such as, for example, withoutlimitation, the pre-failure warning indicator taught in U.S. Pat. No.9,293,028, issued Jul. 16, 2015 with a title, “Roundslings with RadioFrequency Identification Pre-Failure Warning Indicators,” which ishereby incorporated by reference in its entirety.

Referring to FIGS. 1, 2 and 8, an insulated conducting wire 100, such asa twelve-gauge copper wire, may be tied between two eye-loops 27, 29 ona failure indicator system 40 and in parallel with a dedicated strand28. The dedicated strand 28 is preferably positioned within or on thecore 52. The dedicated strand 28 is preferably different from thestrands 54 that make up the core 52. The dedicated strand 28 ispreferably placed proximate the core 52, for example, the dedicatedstrand 28 may be twisted around one or more of the core strands 54 orthe dedicated strand 28 may lay next to the core 52, as illustrated inFIG. 2. In some aspects, the dedicated strand 28 is affixed to theinside of the cover 56. When a roundsling 50 is used over a period oftime, the cover 56 may develop wear points at specific locations, forexample, where the roundsling 10 hangs from a crane's hook. Accordingly,it may be desirable to rotate the cover 56 with respect to theload-bearing core 52. By securing the dedicated strand 28 to the cover56 interior, movement of the cover 56 (either intentionally ornon-intentionally) will typically not impact the operation of thepre-failure indicator assembly 40. When the first eye-loop 27 and secondeye-loop 29 are connected together via a ring 82, the dedicated strand28 plus the ring 82 form an endless loop. The shape of the separatededicated strand 28 generally matches the shape of the endless parallelloops formed by the core strands 54 (e.g., generally circular or oval).The ring 82 may comprise any suitable shape.

The wire 100 preferably serves as a continuity tester. When an overloadsituation occurs, the dedicated strand 28 breaks, preferably at a loadslightly less than the rated load of the strands 54 and the eye-loops27, 29 are thrust apart, resulting in the breakage of the wire 100serving as the continuity tester. The wire 100 is preferably incommunication with the transmitter 20. When the continuity of the wire100 is severed as a result of an overload event, the transmitter 20generates an alert signal and transmits the signal to the receiver 22.The overload signal thus generated may be transmitted using a multitudeof methods (including wired transmission, wireless transmission, lightsignals, audio warnings, and such). The base station 14 may subsequentlyprovide a warning to the operators and riggers or otherwise limitoperation of the lift to prevent breakage of the roundsling 50.

The roundsling 50 may also include an indicator yarn 80. The cover 56may comprise an opening through which the indicator yarn 80 may passthrough, with a length of the yarn 80 and one terminal end thus locatedinside of the cover 56, and a length of the yarn 80 and the otherterminal end thus located outside of the cover 56. The opening may belocated at any suitable position in the cover 56. The yarn 80 preferablyis of a bright color, including yellow, orange, red, or a combinationthereof, or other suitably visible or contrasting color so that a usermay monitor the visible end portion of the yarn 80. For example, in theevent that the roundsling 50 is overstretched or overloaded, the visibleportion of the yarn 80 may become shorter as the yarn 80 is pulled intothe cover 56, with the shortening of the visible section of the yarn 80signaling the user that the roundsling 50 is overstretched oroverloaded. In this sense, the indicator yarn 80 may serve as aredundancy for the failure indicator system 40, as is described above.The indicator yarn 80 may also comprise a component of the failureindicator system 40.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisdisclosure is not limited to the particular embodiments disclosed, butit is intended to cover modifications within the spirit and scope of thedisclosure.

We claim:
 1. An electronic overload inspection and warning system for aroundsling having a strand positioned within a plurality of core strandsand a cover, the system comprising: a wireless sensor system mountableto the roundsling, the wireless sensor system including at least onestrain gauge electrically connected with a wireless transmitter, thestrain gauge measuring strain on the strand; a wireless base stationincluding at least one wireless receiver configured to wirelesslycommunicate with multiple deployed wireless sensor systems; and acarrier element having a first end and a second end, the first endsecured to a first end of the strand and the second end secured to thesecond end of the strand, the strain gauge secured to the carrierelement between the first and second ends of the carrier element.
 2. Theelectronic overload inspection and warning system of claim 1, furthercomprising: an operator terminal including at least a computing devicefor calculating and displaying stress on the roundsling.
 3. Theelectronic overload inspection and warning system of claim 1, furthercomprising: a battery configured to power the strain gauge, the batteryconnected to the roundsling.
 4. The electronic overload inspection andwarning system of claim 3, wherein the battery is configured to rechargewhen subject to vibration.
 5. The electronic overload inspection andwarning system of claim 3, wherein the battery is configured to rechargevia solar power.
 6. The electronic overload inspection and warningsystem of claim 3, wherein the battery is a piezoelectric power cell. 7.The electronic overload inspection and warning system of claim 1,further comprising: an environmental monitoring chip connected to thewireless transmitter, the environmental monitoring chip configured tomonitor at least one of temperature, humidity, pH, ambient visiblelight, ambient ultraviolet light, vibration, conductivity, hazardouschemicals and hazardous gases.
 8. The electronic overload inspection andwarning system of claim 1, wherein the computing device is configuredfor computing a predicted health of the roundsling.
 9. The electronicoverload inspection and warning system of claim 8, wherein the computingdevice is configured to predict the health of the roundsling by at leastreceiving measurements and recording the measurements related to eachcycle and peak loading of the roundsling.
 10. The electronic overloadinspection and warning system of claim 1, further comprising: anindicator yarn connected to the strand at one end and protruding fromthe cover at the other end, the indicator yarn configured to retractinto the cover when the roundsling is subjected to an overload.
 11. Theelectronic overload inspection and warning system of claim 1, whereinthe wireless sensor system and strain gauge are configured to exist in adefault low-power sleep state, the wireless base station is configuredto transmit a wake signal, the wireless sensor system and strain gaugetransferring to a full-powered state upon receipt of the wake signal.12. The electronic overload inspection and warning system of claim 1,wherein the carrier element includes a first hole at the first end and asecond hole at the second end, the first end of the strand connected tothe carrier element at the first hole and the second end of the strandconnected to the carrier element at the second hole.
 13. The electronicoverload inspection and warning system of claim 1, wherein the carrierelement includes a receptacle, the strain gauge secured to the carrierelement in the receptacle, the carrier element has a substantiallycylindrical-shape with rounded first and second ends.
 14. The electronicoverload inspection and warning system of claim 13, wherein thereceptacle is comprised of a flat surface on the carrier element. 15.The electronic overload inspection and warning system of claim 1,wherein the carrier element has a longitudinal axis, the longitudinalaxis extending through the first and second ends, the strain gaugeoriented to measure strain at least along the longitudinal axis.
 16. Theelectronic overload inspection and warning system of claim 1, whereinthe carrier element has a major width measured at one of the first andsecond ends and a minor width measured in a central section of thecarrier element, the major width being greater than the minor width. 17.The electronic overload inspection and warning system of claim 1,wherein the carrier element is mounted within the cover of theroundsling.
 18. An electronic overload warning system for a roundslinghaving core strands and a cover, the system comprising: a wirelesssensor system mountable to the roundsling; a wireless base stationincluding at least one wireless receiver configured to wirelesslycommunicate with the wireless sensor systems; a dedicated strand mountedproximate the core strands, the dedicated strand having a load limitless than a rated load of the core strands; an indicator yarn connectedto the dedicated strand, the indicator yarn including a first terminalend positioned within the cover and a second terminal end positionedoutside the cover; and a wire connected to the dedicated strand andbeing in communication with the wireless sensor, the wire configured tobreak when the dedicated strand breaks, thereby prompting a signal fromthe wireless sensor to the wireless base station, the wireless basestation configured to communicate one of an audible and visual warningto the operator upon receipt of the signal from the wireless sensor. 19.The electronic overload warning system of claim 18, wherein thededicated strand includes a first eye-loop at a first end and a secondeye-loop at a second end.
 20. The electronic overload warning system ofclaim 19, wherein the dedicated strand includes a ring connected to thededicated strand by the first eye-loop and the second eye-loop, the ringhaving the load limit less than the rated load of the core strands. 21.The electronic overload warning system of claim 18, wherein the wire iscomprised of a twelve-gauge copper wire.
 22. An electronic overloadwarning system for a roundsling having core strands and a cover, thesystem comprising: a wireless sensor system mountable to the roundsling;a wireless base station including at least one wireless receiverconfigured to wirelessly communicate with the wireless sensor systems; adedicated strand mounted proximate the core strands, the dedicatedstrand having a load limit less than a rated load of the core strands,the dedicated strand has a dedicated strand rated load and the corestrands have a core strand rated load, the core strand rated load beinggreater than the dedicated strand rated load; and a wire connected tothe dedicated strand and being in communication with the wirelesssensor, the wire configured to break when the dedicated strand breaks,thereby prompting a signal from the wireless sensor to the wireless basestation, the wireless base station configured to communicate one of anaudible and visual warning to the operator upon receipt of the signalfrom the wireless sensor.